Here's a breakdown of the stages:
1. Main Sequence: The Sun is currently in this stage, fusing hydrogen into helium in its core. This will last for about 10 billion years.
2. Red Giant: As the Sun runs out of hydrogen, it will start fusing helium into carbon and oxygen. This will cause the Sun to expand significantly, engulfing Mercury, Venus, and potentially Earth.
3. Planetary Nebula: The Sun will eventually shed its outer layers, forming a beautiful glowing nebula.
4. White Dwarf: The remaining core, composed mainly of carbon and oxygen, will be a very dense and hot object called a white dwarf. This stage can last for trillions of years as the white dwarf slowly cools down.
It's important to note that white dwarfs are not completely "dead". They still contain a vast amount of energy, and some of them can potentially explode as Type Ia supernovae if they are part of a binary system and accrete enough material from their companion star.
So, while the white dwarf stage represents the end of the Sun's active life as a star, it's not necessarily the absolute end of its existence.
